Rivet analyses

title: CRYSTAL_BALL_1990_I294419

Measurement of $R$ for energies between 5 and 7.4 GeV

Experiment: CRYSTAL_BALL (Spear)

Inspire ID: 294419

Status: VALIDATED

Authors: - Peter Richardson

References: - Phys.Lett. B234 (1990) 525-533, 1990

Beams: e- e+

Beam energies: (2.5, 2.5); (2.6, 2.6); (2.6, 2.6); (2.8, 2.8); (2.9, 2.9); (3.0, 3.0); (3.1, 3.1); (3.0, 3.0); (3.2, 3.2); (3.4, 3.4); (3.5, 3.5); (3.6, 3.6); (3.7, 3.7)GeV

Run details: - e+ e- to hadrons and e+ e- to mu+ mu- (for normalization)

Measurement of $R$ in $e^+e^-$ collisions by the Crystal Ball experiment for energies between 5 and 7.4 GeV. The individual hadronic and muonic cross sections are also outputted to the yoda file so that ratio $R$ can be recalcuated if runs are combined.

Source code:CRYSTAL_BALL_1990_I294419.cc

```c++ // -- C++ --

include "Rivet/Analysis.hh"

include "Rivet/Projections/FinalState.hh"

namespace Rivet {

/// @brief R measurement class CRYSTAL_BALL_1990_I294419 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(CRYSTAL_BALL_1990_I294419);


/// @name Analysis methods
/// @{

/// Book histograms and initialise projections before the run
void init() {
  // Initialise and register projections
  declare(FinalState(), "FS");

  // Book histograms
  for (size_t ix = 0; ix < 2; ++ix) {
    book(_c_hadrons[ix], "/TMP/sigma_hadrons_" + toString(ix + 1),
         refData<YODA::BinnedEstimate<string>>(1 + ix, 1, 1));
    book(_c_muons[ix], "/TMP/sigma_muons_" + toString(ix + 1),
         refData<YODA::BinnedEstimate<string>>(1 + ix, 1, 1));
    for (const string& en : _c_hadrons[ix].binning().edges<0>()) {
      double eval = stod(en) * GeV;
      if (isCompatibleWithSqrtS(eval)) {
        _sqs[ix] = en;
        break;
      }
    }
  }
  raiseBeamErrorIf(_sqs[0].empty() && _sqs[1].empty());
}


/// Perform the per-event analysis
void analyze(const Event& event) {
  const FinalState& fs = apply<FinalState>(event, "FS");

  map<long, int> nCount;
  int ntotal(0);
  for (const Particle& p : fs.particles()) {
    nCount[p.pid()] += 1;
    ++ntotal;
  }
  if (nCount[-13] == 1 && nCount[13] == 1 && ntotal == 2 + nCount[22]) {
    // mu+mu- + photons
    _c_muons[0]->fill(_sqs[0]);
    _c_muons[1]->fill(_sqs[1]);
  }
  else {
    // everything else
    _c_hadrons[0]->fill(_sqs[0]);
    _c_hadrons[1]->fill(_sqs[1]);
  }
}


/// Normalise histograms etc., after the run
void finalize() {
  for (size_t ix = -0; ix < 2; ++ix) {
    BinnedEstimatePtr<string> mult;
    book(mult, 1 + ix, 1, 1);
    divide(_c_hadrons[ix], _c_muons[ix], mult);
  }
}

/// @}


/// @name Histograms
/// @{
BinnedHistoPtr<string> _c_hadrons[2], _c_muons[2];
string _sqs[2];
/// @}

};

RIVET_DECLARE_PLUGIN(CRYSTAL_BALL_1990_I294419); } ```